Westminster police used every investigative tool to find a suspect in the Oct. 5 abduction and slaying of 10-year-old Jessica Ridgeway — watching video surveillance, combing through hundreds of license-plate numbers, following thousands of tips and collecting hundreds of DNA samples.

The investigation prompted one of the largest criminal searches in Colorado history, with more than 1,000 law enforcers from 40 agencies deploying everything from high-tech forensic science to neighborhood canvassing.

Yet it was a phone call from Mindy Sigg that led police to arrest her 17-year-old son, Austin. That call came a day after authorities announced a definitive link between Jessica’s death and the May 28 attempted abduction of a jogger — information police had known for more than a week, a source close to the investigation told The Denver Post.

Authorities, citing a judge’s gag order, will not discuss the case with the media, and they have not disclosed what exactly led the mother to call Westminster police about her son.

“Whenever you are talking to the media and giving stuff to the media, you have to think that you are also talking directly to the killer,” said Gregg McCrary, a former FBI profiler from Virginia, who has not had any involvement in this case. “You want to put out things that the people around the killer would know.”

In another example of that type of strategic release of information, police waited until Oct. 19 to reveal they had found the 1½ -inch cross with etched marks that they said “could become a pivotal piece of evidence that helps authorities identify and locate Jessica’s killer.”

Law enforcement sources told The Post that investigators discovered a wooden cross with Jessica’s dismembered body shortly after it was found Oct. 10 near a culvert in Pattridge Park Open Space.

Photos of the cross accompanied a news release and were posted on the department’s Facebook page, which became a useful tool for police to break news to the public.

Where and when the cross was found and how it was connected to the killer were not revealed.

Westminster Investigator Trevor Materasso said later that police saw a spike in tips after the release, but most were fixated on the cross style and not the distinct markings.

“We really want people to look at the markings,” he said.

Retired Denver homicide Lt. Jon Priest said investigators in the Ridgeway case probably tried to balance the importance of keeping the public informed with the release of details that could either turn up the heat on a suspect and encourage him to come forward or backfire and spur him to flee.

“A suspect could say, ‘They’re starting to figure this out. I may need to get out of Dodge,’ ” said Priest, who is not involved with the investigation. “It’s a balancing act.”

The search for Jessica brought in FBI agents, Denver SWAT-team members and officers from throughout the metro region. On the day after she disappeared, nearly 1,000 people showed up at the West View Recreation Center, including many law enforcement officers on their day off.

In the early part of the search, hounds sniffed for evidence between her home and school, and officers questioned registered sex offenders and went door-to-door in the neighborhood. Cellphone records were examined to find people who had been at key sites related to the crime.

Even Austin Sigg was questioned by police, according to 9News, which reported that he let them in the house to look for the girl.

Clark Bechtel, a park ranger and retired Marine who lives across from the Siggs, said that around Oct. 15, FBI agents began knocking on doors, interviewing residents and asking them about their neighbors.

An agent called Bechtel’s employer to check up on him and cross him off their list.

“They were walking up and down the street, gathering lists of people like myself, peeking in backyards and cars,” Bechtel said. “You just felt a blanket.”

Last summer, their cat Chewie disappeared. They later found him cut in half along the footpath that runs behind their house. There’s no telling what happened to the beloved family pet, but it’s the type of incident that leapt to mind when they heard Jessica had been dismembered.

Bechtel told police about it.

Police set up surveillance throughout the Countryside neighborhood, south of Rocky Mountain Metropolitan Airport, with video cameras on nearly every street and police vans that took flash photos of every vehicle driving through.

Naomi Fox, who lives on Sigg’s street, West 102nd Avenue, said police didn’t seem more focused on that stretch — or didn’t seem to have a suspect in mind.

“They had these vans all over,” Fox said.

On Oct. 17, authorities searched Fox’s home, asking whether they had noticed any delivery trucks or laborers in the area lately.

Rebecca Martinez, who lives on the same side of the street as the Siggs, said authorities came to her house Oct. 15, and her husband voluntarily submitted to a DNA test. Her husband fell into the broad age range of the suspect in the May 28 abduction attempt.

Thousands of tips poured into the command center, with police deploying eight people to handle e-mails and calls to the hotline.

Tips were divided into three categories of importance, with Tier 1 tips drawing immediate attention from investigators. But nothing was ignored, Materasso said last week.

Ultimately, though, the break appears to have had little to do with high-tech crime-solving tactics. It came the old-fashioned way.

“The slip-up could be in telling someone,” Priest said, “which is what happened in this case.”

Jeremy P. Meyer was a reporter and editorial writer with The Denver Post until 2016. He worked at a variety of weeklies in Washington state before going to the Walla Walla Union-Bulletin as sports writer and then copy editor. He moved to the Yakima Herald-Republic as a feature writer, then to The Gazette in Colorado Springs as news reporter before landing at The Post. He covered Aurora, the environment, K-12 education, Denver city hall and eventually moved to the editorial page as a writer and columnist.

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